The dates of events more than about 3000 years ago are for the most part speculative. For each of the first civilizations in the Near East the chronology derives mainly from lists of kings, with the passage of time marked by the number of years since the start of each reign..

This gives a reasonably clear idea of the sequence of major events within the single region, but the relating of each region's chronology to those of its neighbours is a haphazard process. It depends on the inscriptions or documents (papyrus scrolls, cuneiform tablets) that happen to have survived and been discovered, together with the further chance of their mentioning contemporary events elsewhere. Even then, it remains a matter of scholarly interpretation, and inevitable disagreement, as to how much reliance can be placed on a particular document.

Discoveries in the Near East in the past century (such as the cuneiform archives of Mari and Ebla) have tended to bring events in the second millennium BC forward by several decades. The period to which others are most often related by scholars is the reigh of the great Babylonian ruler Hammurabi. In older academic works this is given as 1792-1750 BC. More recently a consensus (but not unanimity) has emerged for interpreting his reign as lasting from 1728 to 1686 BC. Events elsewhere in the region are then dated as consistently as possible in relation to this benchmark.

The earlier version is known now as the Long Chronology (it places a longer period of time between events of the second millennium BC and events which can be securely dated in the next millennium). The later consensus is referred to as the Short Chronology, and this is the system followed in HistoryWorld.